1. Field of the Invention
This invention relates to hydraulically actuated systems with changeable fluid filters and particularly to a check valve assembly preventing the loss of the fluid during the service of fluid filters.
2. Description of the Prior Art
The prior art is replete with different hydraulic systems utilizing various designs of check valve assemblies. For example, the U.S. Pat. No. 3,273,715, issued to N. O. Rosaen, discloses fluid filters of the type embodying an axially movable or slidable filter cartridge having indicating means associated therewith. The U.S. Pat. No. 1,782,702, issued to L. H. Wheeler, discloses a liquid handling device having filtering means including a detachable cup and a check valve in a cube unseated by attaching said cup. The U.S. Pat. No. 3,363,762, issued to H. W. Ensign, discloses a removable element filter assembly having flow preventing means in which a pair of automatically operated check valves contained in the strainer body control fluid flow. The U.S. Pat. No. 2,331,119, issued to J. Gouldbourn, et al., specifies a lubricating system having a shut off valve which is rendered operative by the removal of the filter. The U.S. Pat. No. 1,220,231, issued to R. K. Jack, specifies a strainer device having a self-closing valve which automatically shuts off access to the strainer chamber of the oil or other substance. The U.S. Pat. No. 922,657, issued to C. H. Worsey, discloses a strainer for lubricating systems which provides means for insuring continuous flow thereof to the bearings.
However, none of the prior art references of record discloses the novel check valve assembly having an actuator as disclosed in the subject invention.